The present invention is directed generally to the label applying arts and more particularly to a novel and improved automatic labeling system for applying an elongate label to each of a plurality of relatively large objects moving substantially in a straight line past a fixed labeling station.
Labeling machines for automatically applying gummed or adhesive-backed labels to relatively small containers or the like on an assembly line or conveyor are well known. Generally speaking, such apparatus comprises a supply of adhesive-backed labels carried upon a carrier strip comprising an elongate web of release liner material which is fed from a supply reel to a takeup reel, with a suitable label applying device intermediate the two reels. Generally speaking, such a label applying device may include a peeler plate which comprises a plate having a relatively sharply angled edge. The adhesive-backed labels peel or "flag" from the carrier strip as this strip is fed around the sharp edge of the peeler plate. A suitable carrier strip transport device including suitable idler wheels and drive wheels is generally provided for this purpose intermediate the supply reel and takeup reel.
When relatively small objects such as cans, bottles or the like are being labeled this system works quite well. Such relatively small objects may also be readily rotated or otherwise manipulated to aid in receiving labels. Since the relative surface velocity of such small objects does not vary greatly as they rotate and pass by the label applying device, such systems generally work satisfactorily at some a predetermined, constant speed of the web or release liner transport drive. Moreover, suitable mechanical positioning means may be used in conjunction with the conveyor for assuring proper positioning and rotation, if desired, of the relatively small containers to receive the labels from the peeler plate or applying device.
However, a number of problems arise when an analogous labeling system is to be utilized for applying labels to relatively large, heavy objects moving down a conveyor line. For example, relatively large and heavy chemical-containing drums are difficult and sometimes even dangerous to rotate or otherwise manipulate by mechanical means while being carried on a conveyor belt or line. Accordingly, a labeling apparatus at a work station adjacent the conveyor must perform the necessary movements to completely apply labels to the generally cylindrical side surfaces of such drums.
In applying elongate labels to such a moving, curved surface, a number of problems arise. For example, the speed or velocity of the curved surface relative to the label applying device or peeler plate varies considerably as the drum moves by in a generally straight line. More specifically, the required speed of the label to follow this curved surface generally decreases as the drum and curvature of the surface both approach the labeling station and up to the midpoint of the drum. However, this required speed increases past the drum midpoint as both the curved surface and the drum recede from the label applying station. These variations in speed and in particular the increasing speed as the drum recedes causing jamming and tearing of the labels and backing release liner or web, rendering the automatic labeling system inoperative after as few as two or three drums have passed by. Needless to say, stopping the system for rethreading of the label-bearing web or release liner after every second or third item is unacceptable.
Advantageously, we have found that the foregoing problem may be overcome by transporting the label-bearing web at one speed while the curvature of the drum is approaching the applying device and at a second, higher speed as this curvature is receding. Additionally, the drive or feed to the applying device or peeler plate may be halted between drums on the assembly line. Advantageously, we have discovered means for halting the drive while still leaving a portion of the next label flagged out to achieve initial contact with the next drum surface when the next drum reaches the label applying station.
The foregoing requires the addition of a suitable control system for the drive and feeding of the label-bearing web to and through the applying device or peeler plate. However, since such an applying system must also be safe for use in hazardous environments, the control system should preferably be other than electrical. For example, many uses may involve application of labels to drums containing volatile or potentially volatile chemicals. Hence, we have also developed a novel non-electrical, fluidic-mechanical control system.